DE 43 30 668 A1 (WO 95/07162) discloses a U-shaped, or a bridge-shaped, indexable cutting insert for mounting in an end-mill designed for milling thin slots. The cutting insert has a plate-shaped or approximately plate-shaped fixation element disposed between two edge zones of larger cross-section which carry the cutting edges. The end-mill carries a plurality of the cutting inserts, arranged alternately on both sides of its disk-shaped tool body. When mounted, the fixation element abuts a groove in the face of the tool body. Precise finish of the fixation element is essential for providing a tool with an accurate width of cut. This necessitates grinding of the fixation element. Since the support (or fixation) surface of the cutting insert disclosed in DE 43 30 668 A1 is disposed between the two thicker end-zones, an additional, dedicated grinding phase must be executed to polish the fixation element, which is a time-consuming and expensive process.
The cutting insert is clamped to the tool body by means of a clamping screw. To provide secure engagement of the clamping screw in the tool body, a protrusion is formed in the tool body, and a corresponding recess is formed in the fixation element of the cutting insert, as shown in FIGS. 5 and 6 in the above-cited reference. As the fixation element is already the thinnest element in the cutting insert, forming recess therein weakens the cutting insert and complicates manufacturing of the cutting inserts and the tool body.